BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Exception "Bad Application Handle" - why? Goto page 1, 2, 3  Next          BorlandTalk.com Forum Index -> comp.lang.pascal.delphi.misc View previous topic :: View next topic   Author Message Jens Kretzschmar Guest Posted: Mon Dec 15, 2003 4:49 pm    Post subject: Exception "Bad Application Handle" - why? Hello, I have one EXE and one DLL. From within the EXE I am calling two different functions of the DLL - with the same code. Well, of course the handed over parameters differ. But one call works the other does not. It returns a "Bad Application Handle" Exception while I can call the other function of the DLL with the _same_ Handle without problems. If I compile the DLL as an EXE it runs without Problems and Memory Leaks. Has anybody seen this behaviour? Can someone imagine a cause for this problem. Sounds more like a problem of the abstract type... :-( D7 Ent., Win XP Thanks for those daring to answer! ;-) Jens Back to top J French Guest Posted: Mon Dec 15, 2003 6:24 pm    Post subject: Re: Exception "Bad Application Handle" - why? On Mon, 15 Dec 2003 17:49:56 +0100, Jens Kretzschmar <newsposting (AT) 2andfro (DOT) de> wrote: Quote: Hello, I have one EXE and one DLL. From within the EXE I am calling two different functions of the DLL - with the same code. Well, of course the handed over parameters differ. But one call works the other does not. It returns a "Bad Application Handle" Exception while I can call the other function of the DLL with the _same_ Handle without problems. If I compile the DLL as an EXE it runs without Problems and Memory Leaks. Has anybody seen this behaviour? Can someone imagine a cause for this problem. Sounds more like a problem of the abstract type... :-( D7 Ent., Win XP Thanks for those daring to answer! Sounds like faulty parameters in the 'errant' DLL's calling routine Back to top David Reeve Guest Posted: Tue Dec 16, 2003 1:28 am    Post subject: Re: Exception "Bad Application Handle" - why? "Jens Kretzschmar" <newsposting (AT) 2andfro (DOT) de> wrote Quote: Hello, I have one EXE and one DLL. From within the EXE I am calling two different functions of the DLL - with the same code. Well, of course the handed over parameters differ. But one call works the other does not. It returns a "Bad Application Handle" Exception while I can call the other function of the DLL with the _same_ Handle without problems. If I compile the DLL as an EXE it runs without Problems and Memory Leaks. Has anybody seen this behaviour? Can someone imagine a cause for this problem. Sounds more like a problem of the abstract type... :-( D7 Ent., Win XP Thanks for those daring to answer! ;-) Jens Sounds like a problem of confusion between the Application instance of the exe and the Application instance of the dll. The application handle of the dll is normally nil, and I assume you are passing the handle of the main application through for use by the dll. I take it you are assigning the handle you pass to Application.Handle within the dll ? This should be without hazard. Can you post more details? Dave Back to top Terry Russell Guest Posted: Tue Dec 16, 2003 2:01 am    Post subject: Re: Exception "Bad Application Handle" - why? "Jens Kretzschmar" <newsposting (AT) 2andfro (DOT) de> wrote Quote: Hello, I have one EXE and one DLL. From within the EXE I am calling two different functions of the DLL - with the same code. Well, of course the handed over parameters differ. But one call works the other does not. It returns a "Bad Application Handle" Exception while I can call the other function of the DLL with the _same_ Handle without problems. If I compile the DLL as an EXE it runs without Problems and Memory Leaks. Has anybody seen this behaviour? Can someone imagine a cause for this problem. Sounds more like a problem of the abstract type... Presumably 'same code' means the caller not the dll. check function call method/ function declaration model parameter types, parameters passed, parameters as function sees them ( related to declaration and may be difference between exe and dll) Back to top Jens Kretzschmar Guest Posted: Tue Dec 16, 2003 10:09 am    Post subject: Re: Exception "Bad Application Handle" - why? Quote: Sounds like faulty parameters in the 'errant' DLL's calling routine Hi, that seems to be it. I built a new unit with only the called routine (without the functions it calls internally) and it threw the exception. I took out all parameters and it works. Strange enough as there are only simple parameters. When I started programming I learned "Do not pass over strings, use PChar; do not use Boolean, use WordBool, ..." and so on. Did that change in D7 or WinXP? Thanks for your help already! Jens Back to top Maarten Wiltink Guest Posted: Tue Dec 16, 2003 10:23 am    Post subject: Re: Exception "Bad Application Handle" - why? "Jens Kretzschmar" <newsposting (AT) 2andfro (DOT) de> wrote [...] Quote: When I started programming I learned "Do not pass over strings, use PChar; do not use Boolean, use WordBool, ..." and so on. Did that change in D7 or WinXP? That's for when the DLL is provided by Windows; when the DLL is your own and written in Delphi, you can (and should) stick to the language's own types. There's just the heap issue which is sidestepped by using ShareMem. The most common mistake remains calling conventions disparities. Groetjes, Maarten Wiltink Back to top Jens Kretzschmar Guest Posted: Tue Dec 16, 2003 10:55 am    Post subject: Re: Exception "Bad Application Handle" - why? Quote: The most common mistake remains calling conventions disparities. Yes, this was it. I know it would be something incredibly stupid: In the declaration of the called routine in the EXE, the "stdcall" was missing. So parameters were passed Left-to-right ("register") and received Right-to-left. Crash. As long as there was only the Application Handle as Parameter everything was fine, with Application Handle and "WordBool" it still worked but (strange ?!) with three parameters (Handle, Word, WordBool) it crashed. This took me three days and I still don't understand why the version with three parameters crashed (although it is symmetric) and why I got an exception where String Pointers are freed.... ???? Thanks to all of you, thanks a lot! Jens Back to top Jens Kretzschmar Guest Posted: Tue Dec 16, 2003 10:58 am    Post subject: Re: Exception "Bad Application Handle" - why? Quote: check function call method/ function declaration model parameter types, parameters passed, parameters as function sees them ( related to declaration and may be difference between exe and dll) Yes, that was it. In the declaration of the called routine in the EXE a "stdcall" was missing. I wrote more in my answer to Maarten Wiltink's posting. Thanks a lot for your help! Jens Back to top Jens Kretzschmar Guest Posted: Tue Dec 16, 2003 11:00 am    Post subject: Re: Exception "Bad Application Handle" - why? Thanks for your help, Dave. It was an incredibly stupid error - see my posting in reply to Maarten Wiltink's posting. Thanks again, Jens Back to top Jens Kretzschmar Guest Posted: Tue Dec 16, 2003 11:10 am    Post subject: Re: Exception "Bad Application Handle" - why? Quote: As long as there was only the Application Handle as Parameter everything was fine, with Application Handle and "WordBool" it still worked but (strange ?!) with three parameters (Handle, Word, WordBool) it crashed. Just to understand it and for learning: Does one also have to count the return parameter? (Handle): LongInt - works (value definitions alike) (Handle, WordBool): LongInt - works (symmetrical) (Handle, Word, WordBool): LongInt - crashes (asymmetrical) Back to top J French Guest Posted: Tue Dec 16, 2003 12:24 pm    Post subject: Re: Exception "Bad Application Handle" - why? On Tue, 16 Dec 2003 11:09:35 +0100, Jens Kretzschmar <newsposting (AT) 2andfro (DOT) de> wrote: Quote: Sounds like faulty parameters in the 'errant' DLL's calling routine Hi, that seems to be it. I built a new unit with only the called routine (without the functions it calls internally) and it threw the exception. I took out all parameters and it works. Strange enough as there are only simple parameters. When I started programming I learned "Do not pass over strings, use PChar; do not use Boolean, use WordBool, ..." and so on. Did that change in D7 or WinXP? Thanks for your help already! As Maarten has pointed out, you can pass Strings to/from DLLs provided you use ShareMem - basically this involves *another* DLL The problem is that memory manager within the DLL is (normally) totally different from the memory manager in the calling EXE - ie: two Memory Managers Personally I am not that keen on DLLs being 'tied' to the EXEs From messing around I have found that Delphi Strings *can* be safely passed to DLLs - but one should never modify their length - the best thing is to copy them explicitly (byte by byte) - and for safety have them declared as Const Under StdCall a Const String is passed as a pointer to the first byte of its data eg: @S[1] is put on the stack The preceding 4 bytes eg: S[-3] to S[0] contain the length of the String - simply declaring the parameter as: Const S :String gives you a Delphi ANSI String Strings can be returned from DLL Functions (or as Vars) by using OleVariants that actually contain a String Although potentially dangerous, it is very convenient having 'clean' calling parameters for the DLL - even if it involves a bit more work inside the DLL Hence one does not need to use the PChar and 'fill a buffer' approach - ie: the Win API approach - when writing DLLs that can be called from Delphi or VB This is useful if one is mixing different versions of Delphi, or calling Delphi from VB - also calling VB from Delphi Some might say that it is foolish worrying about not being able to send #0 in a string to a DLL without sending a buffer length - I don't agree - DLLs are supposed to 'wrap' problems and provide a very clean user interface, a bit more work within the DLL to make it simple to use, is a small investment. HTH Back to top J French Guest Posted: Tue Dec 16, 2003 12:32 pm    Post subject: Re: Exception "Bad Application Handle" - why? On Tue, 16 Dec 2003 11:55:55 +0100, Jens Kretzschmar <newsposting (AT) 2andfro (DOT) de> wrote: Quote: The most common mistake remains calling conventions disparities. Yes, this was it. I know it would be something incredibly stupid: In the declaration of the called routine in the EXE, the "stdcall" was missing. So parameters were passed Left-to-right ("register") and received Right-to-left. Crash. One other thing Normally I write and compile a *very* simple EXE to act as a testbed for the DLL I am working on. Then set that up as the Host Application under Run/Parameters I then debug the DLL - not the App It normally shows up any parameter problems pretty fast Also, I am inclined to use 4 byte Integers instead of Booleans for returning 'Boolean-ish results' - there are too many types of 'Boolean' knocking around ... Back to top AlanGLLoyd Guest Posted: Tue Dec 16, 2003 1:13 pm    Post subject: Re: Exception "Bad Application Handle" - why? In article <3fdef9da.14213415 (AT) news (DOT) btclick.com>, [email]erewhon (AT) nowhere (DOT) com[/email] (J French) writes: Quote: Also, I am inclined to use 4 byte Integers instead of Booleans for returning 'Boolean-ish results' - there are too many types of 'Boolean' knocking around ... That's a LongBool in Delphi - see Delphi help on "Boolean type". Alan Lloyd [email]alanglloyd (AT) aol (DOT) com[/email] Back to top Jens Kretzschmar Guest Posted: Tue Dec 16, 2003 1:15 pm    Post subject: Re: Exception "Bad Application Handle" - why? Quote: ecx, edx. But - what's more important: With 'stdcall', the callee is meant to clear the stack...and when no stack is used by caller, this will cause exceptions. What will possibly happen is that the exception occurs at some later point in the calling routine, as the stack now may be "too short" That would explain why I get an exception at some point where strings are freed. Thanks! Quote: I'll not spend any money on American Software products until armed forces are out of Iraq. .. PS.: Is someone gonna get those guys out of there soon ? I need to upgrade to Delphi 7 !!! Why don't you wait for Delphi 8? Delphi 7 is included in that package and the armed forces will probably be out of Iraq when the first patch is available.... ;-) Jens Back to top Jens Kretzschmar Guest Posted: Tue Dec 16, 2003 1:22 pm    Post subject: Re: Exception "Bad Application Handle" - why? Quote: One other thing Normally I write and compile a *very* simple EXE to act as a testbed for the DLL I am working on. Then set that up as the Host Application under Run/Parameters I then debug the DLL - not the App I discovered that while I was forking through the help file yesterday. How does that work? I clicked on "Load" and it simply started the EXE. And when I clicked the Button which executed the function calling the DLL it simply crashed. I just tested it with the repaired DLL and it never reaches the breakpoint set at the beginning of the called function in the DLL. Can I debug only in the CPU Window? (So far I just wrote my DLLs as EXE, debugged them and converted them into DLLs afterwards.). Thanks teaching me. ) Jens Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> comp.lang.pascal.delphi.misc All times are GMT Goto page 1, 2, 3  Next Page 1 of 3   Jump to: Select a forum C++ Builder Newsgroups----------------C++ BuilderC++ Builder (ActiveX)C++ Builder (Announcements)C++ Builder (Command Line Tools)C++ Builder DatabasesC++ Builder Databases (ADO)C++ Builder Databases (Desktop)C++ Builder Databases (InterBase Express)C++ Builder Databases (Multi-Tier)C++ Builder Databases (SQL Servers)C++ Builder (Graphics)C++ Builder (IDE)C++ Builder (Internet)C++ Builder (Internet Socket)C++ Builder (Internet Web)C++ Builder (Jobs)C++ Builder (Language)C++ Builder (Language C++)C++ Builder (Compatibility with MFC)C++ Builder (Native API)C++ Builder (Non-Technical)C++ Builder (Students)C++ Builder (Third Party Tools)C++ Builder (Upgrade)C++ Builder (VCL)C++ Builder (VCL Components Usage)C++ Builder (VCL Components Development)C++ Builder (VCL Usage)C++ Builder (WinAPI)C++ Builder Installation Delphi Newsgroups----------------Delphi (General)Delphi ActiveX Controls UsageDelphi ActiveX Controls DevelopmentDelphi As400Delphi DatabasesDelphi Databases (ADO)Delphi Databases (dbExpress)Delphi Databases (Desktop)Delphi Databases (InterBase Express)Delphi Databases (Multi-Tier)Delphi Databases (SQL Servers)Delphi DeploymentDelphi GraphicsDelphi IDEDelphi InternationalizationDelphi InternetDelphi Internet Isapi-WebBrokerDelphi Internet WebSnapDelphi Internet WinsockDelphi JobsDelphi Language BASMDelphi Language ObjectPascalDelphi Model Driven Architecture (General)Delphi Model Driven Architecture (Third Party)Delphi MultimediaDelphi Native APIDelphi Non-TechnicalDelphi ObjectPascalDelphi OLE AutomationDelphi OO designDelphi OpenToolsAPIDelphi Reporting-ChartingDelphi RTLDelphi StudentsDelphi TeamSourceDelphi Thirdparty ToolsDelphi Thirdparty Tools (General)Delphi Thirdparty Tools (IntraWeb)Delphi Thirdparty Tools (RaveReports)Delphi UpgradeDelphi VCLDelphi VCL ComponentsDelphi VCL Components UsingDelphi VCL Components WritingDelphi WebServices SOAPDelphi WinAPIDelphi XMLDelphi Installationcomp.lang.pascal.delphi.components.misccomp.lang.pascal.delphi.components.usagecomp.lang.pascal.delphi.components.writingcomp.lang.pascal.delphi.databasescomp.lang.pascal.delphi.misccomp.sources.delphi JBuilder Newsgroups----------------JBuilderJBuilder AnnouncementsJBuilder Applet IssuesJBuilder As400JBuilder CompilerJBuilder CORBA/RMIJBuilder DatabasesJBuilder DB SwingJBuilder DebuggerJBuilder DeploymentJBuilder DocumentationJBuilder EnterpriseJBuilder HandheldJBuilder IDEJBuilder JavaJBuilder JavaAPIJBuilder Java LanguageJBuilder Java SwingJBuilder Java BeansJBuilder Java Beans UsageJBuilder Java Beans DevelopmentJBuilder JBCLJBuilder JDataStoreJBuilder JobsJBuilder LinuxJBuilder MacintoshJBuilder & MobileSetJBuilder MultiLingual AppsJBuilder Non-TechnicalJBuilder OpenToolsJBuilder Servlets (JSP)JBuilder StudentsJBuilder Team DevelopmentJBuilder Thirdparty ToolsJBuilder UpgradeJBuilder Installation InterBase Newsgroups----------------InterBaseInterBase Bug DiscussionInterBase GeneralInterBase IBConsoleInterBase OpenSourceInterBase ReplicationInterBase SQLInterBase ThirdpartyInterBase Installation Miscellaneous Borland Newsgroups----------------AppCenterAppServerEnteraVisiBroker  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.